I wish I could say that I know how it works. I think it's mostly momentum, like an avalanche, once you gain confidence or the ability to do something that you couldn't do before I had to celebrate. I can't even express the excitement I felt when I could cross my legs again. Then there was the goal to climb a climbing wall (despite my fear of heights I did it). There was the half marathon and many short races. Each time I did something I couldn't do before, it was a chance to celebrate. I kept a journal, and still have it to look at. There are still goals I would like to accomplish.
For the most part, I face my fears and do my best to put them to rest. (OK still dealing with the heights thing) Each step is toward a new day and a better me. It is the only way. It was not only about calories, food and exercise (although its a big part) but dealing with the reason I hid behind my size and my emotions.
For everyone out there trying to lose weight, You can do it. If I did it, so can you. So take my belief in you and use it until you have it in yourself. Share you victories!